The third generation of photovoltaic technology aims to reduce the fabrication cost and improve the power conversion efficiency (PCE) of solar cells. Singlet fission (SF), an efficient multiple exciton generation (MEG) process in organic semiconductors, is one promising way to surpass the Shockley-Queisser limit of conventional single-junction solar cells. Traditionally, this MEG process has been observed as an intermolecular process in organic materials. The implementation of intermolecular SF in photovoltaic devices has achieved an external quantum efficiency of over 100% and demonstrated significant promise for boosting the PCE of third generation solar cells. More recently, efficient intramolecular SF has been reported. Intramolecular SF materials are modular and have the potential to overcome certain design constraints that intermolecular SF materials possess, which may allow for more facile integration into devices.

•[3,3]Metaparacyclophanes have been used as bridge ligands.•Single crystal X-ray structures are obtained for all of the complexes.•Substituent effect of intramolecular edge-to-face interactions has been studied.•–CN, –NO2 substituents can enhance the stabilities of mono oxidized species.A series of [3,3]metaparacyclophanes bridged bimetallic ruthenium complexes have been designed, synthesized and characterized. 1H NMR and X-ray crystal structure studies revealed that there are prominent intramolecular edge-to-face interaction in these diruthenium complexes, both in the solution and solid states. Electrochemical analyses indicated that the electron-withdrawing substituent groups (–CN, –NO2) can enhance the thermodynamic stability of corresponding mixed-valence species.The intramolecular edge-to-face interactions within the bridging ligand have been well established by single crystal X-ray structure analysis. Substituent effects on the electronic properties of these bimetallic complexes have been studied by UV-Vis and cyclic voltammetry.

A series of substituted dithia[3.3]paracyclophane-bridged binuclear ruthenium vinyl complexes have been synthesized by insertion reactions of [RuHCl(CO)(PPh3)3] with the appropriate dialkynes. The products have been characterized by physico-chemical and spectroscopic methods. In addition, the structure of one complex has been determined by X-ray crystallography. Electrochemical studies have shown that all of the substituted complexes exhibit smaller ΔE values relative to the unsubstituted complex. Photoluminescence studies indicated that all of the examined substituent groups act as “quenchers,” except for the methoxy group.